A link aggregation group (Link Aggregation Group, LAG) is defined by an IEEE 802.3ad standard: Multiple Ethernet (Ethernet) links between two directly connected communication devices may form an aggregation relationship. FIG. 1 shows the case that two devices are connected through two Ethernet lines. Two physical ports on either of the two devices are bundled together to form one logical port. The two Ethernet links are aggregated into “one” logical link for the two devices. This provides convenience for high-layer protocol communication and traffic forwarding.
In the method for link aggregation failure protection in the prior art, as shown in FIG. 2, device 3 (Device3), device 4 (Device4), and device 5 (Device5) are all connected to two aggregation devices (AGG Device) AGG1 and AGG2, and forward data through the aggregation devices. Two physical links on device 3, device 4, and device 5 separately form an LAG. After an aggregation device receives a data packet sent by device 3, device 4, or device 5, the aggregation device looks up its own MAC address table according to the MAC (Media Access Control, MAC) address carried in the data packet and forwards data. Normally, the link between the two aggregation devices is in the closed state. When one physical link fails, for example, the link between device 4 and AGG1 fails, AGG1 sends all the data sent to device 4 to AGG2, and AGG2 forwards the data according to the media access control address, and sends the data to device 4.
In the prior art, the two aggregation devices need to notify each other of information about reachability of the MAC address so that normal forwarding of data may be ensured when a failure occurs. However, the MAC address table is a dynamic table and real-time learning and aging are required. Therefore, synchronization of MAC addresses of the two aggregation devices cannot be ensured, and thereby normal sending of data can hardly be ensured when the link fails.